Changes the genesis generation in `op-chain-ops` so that the L1 genesis
includes shanghai. This impacts `op-e2e` that uses the libraries in
`op-chain-ops` such that now `op-e2e` will run with shanghai enabled
for L1. Note that shanghai is not yet enabled on L2. This commit
updates the `fakepos` utility to use the post shanghai execution api.

This commit also deletes the `fork_test` in which a test existed for
the upgrade to shapella but has already happened. Keeping that test
around adds extra burden to the maintainers and isn't particularly
necessary to keep around anymore now that the network has upgraded
successfully.
Co-authored-by: protolambda <proto@protolambda.com>